Artificial snow



` ARTIFICIAL snow Filed oct. 1s. 196s Pfg.

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ATTORNEY United States Patent O 3,443,492 ARTIFICIAL SNOW Charles M.Pleass, 17 Ambar Place Bernardsville, NJ. 07924 Filed Oct. 13, 1966,Ser. N0. 586,517 Int. Cl. E04c 1/24; A63g 21 /02; C08h 13/08 U.S. Cl.94-3 5 Claims ABSTRACT OF THE DISCLOSURE A synthetic skiing surfacewhich comprises a plurality of Iparticles such as sand, pea gravel andmaterials havlng generally the particle size distribution of corn snow,each particle being coated with a substantially continuous hardenedplastic coating of the organic class known as the polyolefins, with thepreferred member of this class being polyethylene, or other polymericorganic coatings having substantially the same properties aspolyethylene with respect to coefficient of friction and resistance toweathering. The thickness of the coating is sufficient to render to thecomposite particles surface properties which are equivalent to those ofthe plastic chosen, particularly to provide a coefficient of frictionapproximating that of a film of water, and a composite particle densitywhich approximates the density of corn snow. The depth of the particlesis sufficient to pack and simulate a corn snow condition.

This invention relates to a novel and improved snowlike material forskiing particularly suitable for year round use.

It is known to employ artificial materials for skiing, and suchmaterials as saw dust and wood pulp have been tried. Use has also beenmade of plastic mats, sand, plastic particles and oil coated gravel. Upto the present time, no proposed artificial surface has obtainedsubstantial commercial acceptance.

For instance, the bulk density of plastic in powder form is too lowandthe powder is particularly susceptible to the action of wind.Prefabricated plastic mats normally prepared on a `flexible backing lackthe aesthetic appeal of natural snow, are relatively expensive tomanufacture, and cannot be used under a natural covering of winter snowwithout receiving irreparable damage from heavy conventionalsnow-leveling equipment. Sand and oil coated gravel are abrasive toconventional ski equipment. Other materials used have suffered fromsimilar problems.

Corn snow is a very common surface for skiing, and actually consists ofsmall particles of ice. The mechanism which makes skiing on corn snowpleasant is that the pressure of the skis on the ice particles causesthe formation of a thin film of water which acts as a lubricant.Otherwise, the hardness of the ice would quickly abrade the bottoms ofthe skis, and it is a known fact that if ambient temperatures areextremely low, too low for this formation of water, the skis hardlymove.

The reason why oil coated sand probably is unsatisfactory is that thepressure of the skis on the sand probably displaces the oil filmexposing the sand particle surface. As this surface has an extremelyhigh coefficient of friction, the skis hardly move and excessive wear isexperienced.

Accordingly, it is an object of the present invention to provide aninexpensive artificial snow which overcomes the disadvantages of knownmedia, and in particular, it is an object of the invention to provide anartificial snow which packs similarly to natural snow and thereforeapproximates the characteristics of natural snow, in appearance, and infeel or movement in -response to the pressure of ski edges.

It is further an object of the present invention to provide anartificial snow which is non-abrasive to skis and clothing.

It is a further object of the present invention to provide an artificialsnow which can be left in place during winter months and which willresist the adverse sources of wear to which it may be subjected, forinstance, ultra violet degradation.

In accordance with the above objects, the artificial snow of the presentinvention comprises a layer of particles, each particle comprising sand,pea gravel or the equivalent, coated with a plastic sufficiently thickto entirely cover the sand or gravel surface, i.e., sufficiently thickto render to the surface of the particles properties which areequivalent to those of the plastic chosen. The sand or gravel may beselected to include a range of sizes to meet packing conditions requiredof a specific application. For instance, steep slopes would require ahigher bulk density of the layer of particles than gentle slopes.Preferably the sand or gravel size range in diameter from about 0.25inch to about .010 inch. The thickness of the plastic may be about onetenth of the diameter of the average sand or gravel piece.

The invention and advantages thereof will become more apparent uponconsideration of the following specification with reference to thedrawing, in which FIGURE 1 is a sectional view showing a ski slopecovered with particles in accordance with the invention, and

FIGURE 2 is a partial section View showing coated particles inaccordance with the invention.

Referring to the drawing, the artificial snow of the invention covers abase, the snow comprising a large number of particles of sand or peagravel covered with a plastic coating. Pea gravel is a well-known termused in the trade to designate natural gravel or crushed rock of aparticle diameter approximately 0.25 inch. Smooth surf washed varietiesform an effective embodiment of the present invention beingintrinsically smooth. Pea gravel has the advantages over sand that it isless expensive to coat to a given thickness, the surface to volume ratiobeing low, and agglomeration is less likely. Preferably the sand islight in color with grains also rounded by natural erosion. Such sand orpea gravel can normally be found on ocean beaches and generally -willhave a satisfactory particle size distribution without the need forclassifying. The particles will normally vary in diameter from 0.010inch for sand and up to 0.25 inch lfor pea gravel. Ski slope and skiingconditions may dictate the particular ranges of particle sizes mostsuitable. For instance, steep slopes may require a higher bulk densityt0 meet packing conditions and resist skiing-off, i.e., removal of thesnow covering by the combined action of gravity and movement of theskiers, whereas gentler slopes for instruction may require a lesscritical range of particle sizes. For the former, the heavies densityfiner sand may be required, whereas for the gentler slope, the lesserexpensive pea gravel (i.e., less expensive to coat) may be satisfactory.In either event, the bulk density provides a superb surface whichclosely simulates actual packed snow, including such formed mounds knownto skiers as moguls Plastic coatings may be of any conventional typewherein the coefficient of friction approximates that of water on ice,for instance polyethylene or its analogues, or methacrylate or itsanalogues, which can be satisfactorily applied to the sand. Preferably,the coatings are white, or near white. An ultra violet absorber wouldnormally be included in the plastic formulation. Polyethylene isparticularly suitable becauseit is inexpensive, readily applied, wearresistant, and particularly resistant to ultra violet degradation withsuch an absorber. The density of polyethylene coated sand approximatesthe density of particles of corn snow.

A number of coating methods are available. The coating may be applied bydissolving the plastic in a solvent, and evaporating the latter in thepresence of the sand in a tumbling device (for instance a cement mixer).AS another method, the polymeric plastic can be created from a suitablemonomer or low molecular weight precursor by catalytic action in thepresence of the sand to be coated, either with or without a solvent.Further, the coating can be accomplished by dispersion of plasticparticles over the surface of the sand or pea gravel in an agitated bed(a fluid bed) held at an elevated temperature sufficient to render theplastic fluid.

All of these methods will result in a substantially uniform coating thethickness of which may be readily controlled. This thickness should bein the order of a tenth of the diameter of the average sized particle inthe range selected.

The present invention has a number of substantial advantages over priorartificial skiing surfaces. The plastic coated particles of theinvention are resistant to weather and sun light, including temperatureextremes, and are capable of withstanding the wear from frictionalcontact with skis, or from the abrasion of mechanical equipment designedfor leveling, packing or movement on artificial snow.

The artificial snow of the invention also is particularly suitable inthat it packs similarly to natural snow (particularly corn snow) andmoves in a natural way in response to the pressure of ski edges. Theartificial snow also approximates the visual characteristics of naturalsnow and thus is aesthetically desirable.

As a further advantage, the plastic coated particles provide minimalfriction when in contact with skis approximating the friction of naturalsnow and thus the feel btained from natural snow.

A further advantage is that the artificial snow of the present inventionpresents a surface which will not injure a skier who has fallen, orcause abrasion or damage to clothes. Also the artificial snow presents asurface which will accept natural Winter snow and allow free permeationor drainage of water formed during melting of the natural snow. In thisrespect, it is apparent that the artificial snow particles, if dispersedamong natural snow, will not detract from skiing enjoyment. Should anarea of a ski slope become bare of natural snow, through wind, or fromexcess use by skiers, the damaged area can be quickly covered with thesynthetic snow of the invention. As a particular advantage, prior towinter, areas of known ice formation from springs can be covered withartificial snow. This provides a means for draining the areas,inhibiting or preventing contact between ground water and natural snow,which is the normal mechanism involved in the growth of sheet ice.

A further advantage is that, if desired, conventional mechanicalcleaning equipment can be used to remove the artificial snow particlesfrom a slope.

A further advantage is that, if necessary, mechanical cleaningequipment, functioning on the principle of cyclone separation, can beused to remove trash from the surface of the artificial snow in a slope,leaving the surface intact.

Although the invention has been described with respect to particularembodiments, variations within the scope of the following claims will beapparent to those skilled in the art.

What is claimed is:

1. A synthetic skiing surface comprising a plurality of compositefree-flowing particles;

each composite particle comprising a core particle of the classconsisting of sand, pea gravel, and materials having generally theparticle size distribution of corn snow, said core particles having adiameter in the range of approximately 0.01 inch to approximately 0.25inch; and

a relatively thin continuous fused layer of cured hardened plastic whichis non-tacky individually and completely enclosing each of said coreparticles, said plastic being of the group consisting of polyethyleneand polymeric organic coatings having substantially the same propertiesas polyethylene with respect to the coefficient of friction andresistance to weathering;

said fused layer being sufficiently thick to render to the surface ofsaid composite particles properties which are equivalent to those of theplastic chosen, but sufficiently thin such that the composite particleshave a density approximating that of corn snow;

said plastic further having a coefficient of friction approximating thatof a film of water;

the depth of the particles being sufficient to pack and simulate a cornsnow skiing condition.

2. A skiing surface according to claim 1 wherein the thickness of theplastic layer is approximately one tenth of the average core particlediameter.

3. A skiing surface according to claim 2 wherein said plastic coating iswhite, said particles being light colored before coating.

4. A skiing surface according to claim 2 wherein said coating is of theclass consisting of polyethylene, analogues of polyethylene,methacrylate, or analogues of methacrylate, in which suitable ultraviolet absorbing compounds are incorporated.

5. A synthetic skiing surface comprising a plurality of compositefree-flowing particles;

each composite particle comprising a core particle of the classconsisting of sand and pea gravel obtained from surf washed areaswherein said particles have a particle sized distribution in the rangeof approximately 0.01 inch to approximately 0.25 inch without the needfor classification;

a relatively thin continuous fused layer of cured hardened plastic whichis non-tacky individually and completely enclosing each of said coreparticles, said plastic being of the group consisting of polyethylene,and polymeric organic coatings having substantially the same propertiesas polyethylene with respect to coefficient of friction and resistanceto weathering;

said fused layer having sufficient thickness to render to the surface ofsaid composite particles properties which are equivalent to those of theplastic chosen, but being sufficiently thin such that the compositeparticles have a density approximating that of corn snow;

said particles having sufficient depth to pack and simulate a mobilecorn snow skiing condition.

References Cited UNITED STATES PATENTS 2,888,418 5/1959 Albanese 260-283,020,811 2/ 1962 Lincoln et al. 94-3 3,026,938 3/1962 Huitt et al.117-100 3,066,580 12/.1962 Alberti 94-3 3,091,998 6/1963 Wehr et al.94-3 3,112,681 12/1963 Gessler et al 94-3 X 3,148,169 9/1964 Martens etal 117-100 3,291,486 12/1966 Applegath et al.

JACOB L. NACKENOFF, Primary Examiner.

U.S. Cl. X.R.

